Methodology
A transparent explanation of the evidence, safety rules, confidence labels, and limitations behind each compatibility report.
Methodology last reviewed September 29, 2026.
The structured model evaluates preferred temperature and pH overlap, temperament and aggression, social or schooling needs, adult-size predation risk, and minimum aquarium requirements. Contextual rules also consider hardness, flow, activity and feeding speed, swimming zone, territory footprint, breeding aggression, specialist setups, invertebrate safety, and vulnerability to fin-nipping.
Matching temperature or pH cannot cancel a serious behavioral or predation risk. Hard safety constraints cap the verdict when the data identifies prey-size differences, a fin-nipper paired with a vulnerable fish, opposing temperature categories, species-only behavior, severe aggression, or overlapping high-intensity territories.
Less severe issues—such as limited parameter overlap, group-size requirements, feeding competition, or a specialist habitat—produce a conditional result instead of being hidden inside a numeric score.
High, moderate, and limited confidence describe completeness of the underlying species records. They do not predict a percentage chance that two individual animals will coexist. A complete record can support a confident “not recommended” verdict, while missing traits prevent an unconditional recommendation.
Species records can include source references for care ranges and husbandry traits. Those references are listed on compatibility reports when available. A reviewed expert override may replace the computed verdict for a specific pair; the report labels that source and displays the reviewer's note. Computed evidence remains visible as context rather than being silently discarded.
GuideMyTank runs the engine across every canonical species pair and maintains a reviewed regression set covering community fish, predators, fin-nippers, territorial species, temperature conflicts, invertebrates, and schooling requirements. A model change must keep those expected outcomes within their reviewed safety bounds.
Confirm both species' care requirements, quarantine new livestock, introduce animals gradually, observe feeding and stress, and keep a safe separation plan. Do not use a compatibility report as a reason to ignore direct aggression, injury, weight loss, hiding, or poor water quality.
See the broader GuideMyTank disclaimer or return to the Compatibility Checker.